New Horizons Jupiter Encounter Timeline

A year after its launch on January 19, 2006, New Horizons is fast closing in on Jupiter, the first target on its near decade-long journey. On February 28 the spacecraft will approach to within 2.3 million kilometers (1.4 million miles) of Jupiter before speeding along on to its way to the edge of the solar system. During the flyby, New Horizons will conduct around 700 separate observations of the giant planet. In addition to providing a gravity assist that shortens New Horizons' journey to Pluto by three years, the flyby serves as a dress rehearsal for the Pluto encounter, which is still more than eight years away. Many of the science observations will serve double duty, revealing new information about Jupiter and its moons at the same time as they test instrument operation modes and sequences for eventual use in the Pluto flyby.

The early part of the Jupiter flyby is dominated by observations with the Long-Range Reconnaissance Imager (LORRI), a black-and-white, high-resolution camera. Beginning about a week before closest approach, New Horizons' other science instruments come in to play. Alice is an ultraviolet spectrometer that will be used to capture images and to perform stellar occultations, watching stars pass behind Jupiter and its moons and using the winking starlight to probe their atmospheres. Ralph is a multispectral imager with two components, called MVIC and LEISA, that will study the composition of the surfaces of the moons and peer to some depth in Jupiter's atmosphere. And about once a day, the spacecraft will turn to Earth to relay data to the Deep Space Network, whose giant radio dishes can perform precise tracking of the spacecraft to monitor its trajectory.

Jupiter rotation movie (LORRI)Range 81,622,011 km; phase 9.4°; 3.6°S, 249.8°W As New Horizons approaches Jupiter, it will use its long-range imager to capture six sets of 11 hourly images, which can be assembled into movies showing the planet's rotation and, occasionally, the passage of the Galilean moons in front of and behind the planet.

Callirrhoe optical navigation (LORRI) In a test of New Horizons LORRI's ability to perform optical navigation with a small, dim Kuiper Belt Object as a target, LORRI will observe Jupiter's outer irregular satellite Callirrhoe, a tiny rock 7 kilometers in diameter that orbits about 25 million kilometers from the planet.

"Kodak moment": Shadows of Io and Ganymede on Jupiter (LORRI)Range 68,135,166 km; phase 9.7°; 3.6°S, 179.5°W This is the first of seven observations during the encounter, referred to as "Kodak moments," that have been planned entirely for their expected aesthetic value.

"Kodak moment": Jupiter full disk (LORRI)Range 29,079,744 km; phase 8.7°; 4.0°S, 263.9°W At this distance, Jupiter's globe will entirely fill the field of view of the long-range imager.

Feb 22 16:23

-5.55

Stellar occultation by Jupiter, ingress (Alice) Range 9,597,585 km; phase 2.4°; 5.2°S, 0.2°W The ultraviolet spectrometer will stare at a bright star as it appears to sink beneath Jupiter's limb. Stellar occultations provide information on the composition, temperature, density, and structure of the upper atmosphere of a planet.

Feb 22 23:35

-5.25

Stellar occultation by Jupiter, egress (Alice) Range 9,116,194 km; phase 2.9°; 5.3°S, 262.4°W Alice will watch as the same star rises from the limb on the other side of Jupiter.

February 24

Space- craft time (UTC)

Days to Jupiter Closest Approach

Event

00:40

-4.21

Io imaging: Pele on limb (LORRI, Alice)Range 7,856,307 km; phase 4.8°; 5.4°S, 340.2°W Lots of Io imaging is planned in order to check whether the many volcanoes discovered by Voyager and monitored by Galileo are active or dormant, and to search for changes in surface features that may have resulted from volcanic activity in the years since Galileo's demise. Researchers will examine Io's limb to look for telltale plumes signifying volcanic eruptions.

Rings: search for embedded ringmoons (LORRI) Because of its communications problems, Galileo was unable to perform searches for as-yet-undiscovered moons in Jupiter's ring system. New Horizons will perform the most detailed survey of Jupiter's rings to date: LORRI will take 49 images over 8 hours.

Ring imaging (for phase curve) (LORRI) Range 5,799,275 km; phase 11.7°; ring opening angle 6.3° The light-reflecting properties of the icy and dusty surfaces of the particles in Jupiter's rings are highly dependent upon the phase (illumination angle) at which the observations are performed. LORRI will perform six detailed surveys of the ring system throughout the flyby to build up a detailed data set on how the brightness of the rings changes with changing phase.

Ganymede eclipse (MVIC, LEISA, LORRI, Alice) Range 6,395,720 km; phase 10.8°; 5.5°S, 348.3°W New Horizons will watch with all its instruments as Ganymede's orbit takes it into Jupiter's shadow; eclipse observations are planned for all four of the Galilean satellites. They enable a search for faint auroral emissions where sunlight would otherwise drown them out. Scientists will also be able to deduce some properties of the moons' tenuous atmosphere from the way its temperature drops as the moon's surface suddenly cools.

Callisto spectroscopy vs. phase (LEISA, LORRI, Alice) Range 6,715,734 km; phase 17.7°; 4.7°S, 2.4°W New Horizons' scientists plan to use the shape of water ice features visible in the spectra of Pluto and Charon to map the surface temperatures on those worlds. At Jupiter, they will perform similar observations at Callisto. The Callisto observations will be performed three times at different phase angles (Sun-moon-spacecraft angles). Scientists seek to understand whether properties besides temperature -- such as phase angle -- can affect the shape of the water ice spectral features and confuse their attempts to map temperature.

18:05

-2.48

Europa terminator topography (LORRI, Alice)Range 4,179,555 km; phase 19.8°; 7.7°S, 164.4°W New Horizons will target the terminator -- the boundary between day and night -- in order to use long twilight shadows to emphasize subtle topographic features on the smooth moon.

18:35

-2.46

Europa composition (anti-Jupiter hemisphere) (LEISA, LORRI, Alice) Range 4,142,772 km; phase 19.8°; 7.7°S, 166.5°W This is one of several surveys designed to fill in gaps in the maps of Jupiter's moons that remain after the end of the Galileo mission.

Stellar occultation by Io (LORRI, Alice)Range 4,546,235 km; phase 25.34°; 6.6°S, 35.1°W Just as stellar occultations by Jupiter can be used to probe the planet's atmosphere, so can the extended atmosphere around Io and the other Galilean satellites be probed.

Turn to Earth for communication session with the DSN New Horizons will spend more than 8 hours pointed at Earth.

17:35

-1.50

Jupiter: Little Red Spot near terminator (LORRI) Range 3,457,024 km; phase 31.5°; 7.7°S, 257.2°W New Horizons must study this newly-formed red spot (more officially known as "Oval BA") when it is near the terminator, or day-night boundary, because Jupiter is much brighter than the Kuiper Belt Objects LORRI is designed to study. LORRI can observe Jupiter at its brightest only when it doesn't fill LORRI's detector; if it fills the field, the detector will be saturated, reducing the usefulness of the images.

Jupiter storm evolution experiment (LEISA)Range 3,353,109 km; phase 33.2°; 7.8°S, 328.0°W This is the first of four observations designed to study a complex structure in Jupiter's clouds: the turbulent wake region behind the Great Red Spot. To scientists' surprise, early New Horizons images have shown that the formerly turbulent region is now clear and smooth! The clear sky should result in LEISA being able to penetrate to a greater depth in Jupiter's atmosphere than had initially been expected.

Elara imaging (phase coverage) (LORRI) Range 15,213,783 km; phase 10.4° Elara is a prograde irregular satellite of Jupiter that is 78 kilometers in diameter. At this range, its disk is almost exactly the same size as one LORRI pixel. LORRI's images may not show much detail on Elara, but the measurements will provide valuable information on the tiny moon's phase curve.

Himalia imaging (phase coverage) (LORRI) Range 14,868,883 km; phase 11.1° Himalia is a prograde irregular satellite of Jupiter that is 184 kilometers in diameter. At this range, its disk is slightly more than two LORRI pixels across. The Himalia studies will be similar to those of Elara, mentioned above.

Turn to Earth for communication session with the DSN New Horizons will spend more than 8 hours pointed at Earth.

11:00

5.22

Elara imaging (phase coverage) (LORRI) Range 5,828,699 km; phase 90.7° At its closest to Elara, New Horizons will achieve a resolution of about 29 kilometers per pixel. Elara will be not quite 3 pixels across.

Himalia imaging (phase coverage) (LORRI) Range 5,455,777 km; phase 78.5° At its closest to Himalia, New Horizons will achieve a resolution of about 27 kilometers per pixel. Himalia's disk will be not quite 7 pixels across.